An organic thin film transistor (OTFT) is a logic unit device using an organic semiconductor for an active layer, has advantages of being adaptable for large-scale processing, being applicable for flexible substrates, low process cost, etc. and presents application prospect in the fields of flat panel display, sensor, storage card, radio frequency identification tag, etc. Research and development of organic thin film transistors have obtained worldwide attention.
Generally, an organic thin film transistor array substrate comprises a source electrode, a drain electrode, a data line, a pixel electrode, a gate electrode and a gate line, an organic semiconductor layer, a gate insulating layer, a passivation layer, etc.
In the course of manufacturing the organic thin film transistor array substrate, it is usually necessary to form a pattern layer of source electrode and data line, a pattern layer of drain electrode, a pattern layer of pixel electrode, a pattern layer of gate electrode and gate line, the organic semiconductor layer, the gate insulating layer, the passivation layer and so on.
For forming each of the layers, one patterning process is to be conducted, and use of a mask plate is required in the patterning process. For example, when the pattern layer of source electrode and data line is formed, firstly, a layer of metal thin film is formed on the array substrate, a layer of photoresist is spin-coated on the metal thin film, next, the photoresist is exposed with a mask plate and developed, then the array substrate is etched with a photoresist pattern to etch away the metal thin film in a photoresist removed area, and finally, the remaining photoresist is removed. Up to here, through exposure and development, etching, stripping and other operation(s), the pattern layer of source electrode and data line is formed on the array substrate. The forming process for every other pattern layer is similar.
In the prior method, for forming each of the layers on the organic thin film transistor array substrate, one patterning process needs to be conducted. It is necessary for each of patterning processes to transfer a mask pattern into a thin film pattern, and it is necessary for each pattern layer to cover another thin film pattern layer precisely, and therefore, in the course of fabricating the organic thin film transistor array substrate, the number of the used mask plates is relatively large. Thereby, the production efficiency is low, which leads to a higher production cost.